Research ArticleArticles

Considerations Of Microclimate-Leaf Disease Relations in Arboriculture

Kenneth J. Kessler, Jr.
Arboriculture & Urban Forestry (AUF) July 1981, 7 (7) 169-173; DOI: https://doi.org/10.48044/jauf.1981.040

Article Figures & Data

Figures

  • Fig. 1.
    Fig. 1.

    Typical sequence of events from time a fungal spore arrives on leaf surface to beginning of entry into leaf. A. Spore arrives. B. Spore becomes swollen. C. A germ tube is produced. D. An attachment to the leaf is formed. E. Penetration into the leaf at the attachment location occurs. Until this time, drying of the leaf surface would terminate the germination-host penetration sequence.

  • Fig. 2.
    Fig. 2.

    Trees growing in an urban situation where buildings and pavement modify microclimate.

Tables

  • Table 1.

    Some natural site situations in relation to likelihood of disease.

    LocationPrincipal advantagePrincipal disadvantageDisease likelihood
    Open-grown isolated trees, level groundTrees are isolated from other treesConditions for dew formation on leavesS1 + + +3 L2 +
    Trees in forest with closed canopyDew formation minimal on understoryUnderstory trees readily infected from diseased overstoryS + + + S +
    Small trees in forest openingCool shaded environment (good for reducing diseases which can be surpressed by shading)Optimum conditions for dew formation on leaves; slow drying conditionsS,L + + + +
    Kettle holeConditions for dew formation optimalS,L + + + + +
    Even-aged trees of same species in a hedgerowDisease can spread easily from tree to treeS,L + + +
    Uneven-aged trees of different species in a hedgerowRapid drying of foliage after wettingHumid zone on lee side of hedgerowS + + L +

    • ↵1 S = tree less than 3 feet tall.

    • ↵2 L = tree taller than 3 feet.

    • ↵3 += least disease, + + + + + = most disease.

  • Table 2.

    Landscaping situations in relation to likelihood of disease.

    LocationPrincipal advantagePrincipal disadvantageDisease likelihood
    S side of buildingrapid foliage dryingHigh air and soil temperatures+ + +1
    N side of buildingCool air and soilSlow foliage drying+ + + +
    E side of buildingMost rapid foliage drying in morningShaded for part of day+ +
    W side of buildingDelayed dew formation in eveningShaded for part of day+ + +
    Around pond edgeDew formation inhibitedSlow drying of wet foliage+ + +
    Paved terrace with tree openingsRapid foliage drying+

    • ↵1 + = least disease, + + + + = most disease.

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Considerations Of Microclimate-Leaf Disease Relations in Arboriculture
Kenneth J. Kessler
Arboriculture & Urban Forestry (AUF) Jul 1981, 7 (7) 169-173; DOI: 10.48044/jauf.1981.040
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